Recently, secondary battery manufacturers are introducing home energy storage system (ESS) packs as new products. The ESS pack stores electricity during day time by using a lithium ion battery and is used when necessary to reduce electricity costs. For example, a lithium ion battery stores electricity generated by using solar panels, wind power or the like, and the stored electricity is used when necessary.
The home ESS pack may be fabricated in a wall-hanging form and installed on a wall or pillar of an indoor or outdoor for user convenience and space utilization. In this case, a wall-hanging bracket suitable for the characteristics of the product may be added in general.
The home ESS pack approximately has a size of about 120×80×20 cm and a weight of about 100 kg, and several home ESS packs may be used in succession.
Depending on storage capacity, the ESS pack may be configured differently in size and weight. For example, a home ESS pack having a built-in DC-DC converter is fabricated larger than a home ESS pack without a DC-DC converter.
Meanwhile, the home ESS pack case is configured so that upper and lower covers are assembled in a case body 1. Since the conventional case body is integrally manufactured by means of extrusion molding (see FIG. 1), it is very difficult to widen the width in a lateral direction (an X-axis direction), among its length, width and height. Thus, the conventional ESS pack case has a large space restriction when additional electric components such as a DC-DC converter are included.
In addition, in a flame spread resistance test (a test to check whether flame is exposed out of a pack case after an ignition occurs inside the pack case), which is one of certification tests for product performance and safety (for example, UL certification), since the conventional ESS pack is manufactured using an integrally extruded case, if an ignition occurs inside the pack case, the pack case is easily deformed due to the increase of pressure caused by the generated gas. As a result, the conventional ESS pack often fails the certification tests.